Noninflammable photographic film



Patented Sept. 13, 1932 UNITED STATES PATENT! OFFICE T LOUIS WESTON, OF LONDON, EltTGLAND NONINFLAMMAIBLE PHOTOGRAPHIG FILM No Drawing. Application filed July 5, 1928, Serial No. 290,711, and. in Great Britain January 5, 1928;

The present invention relates to non-inflammable photographic films and has for its object the manufacture of improved photographic films of this kind.

Non-inflammable films madefrom acetatecellulose with theadmixture of aryl-phosphates to increase their non-inflammability and of plasticizers as aryl-ethers or alcohols, with or without the addition of ammonia compounds and glycerine esters, and coated with sensitive photographic emulsion, suffer a considerable amount of shrinkage and crinkling when submitted to the usual treatment of developing, fixing and washing, to such an extent that this will interfere with the life of the film (particularly in the case of cinematographic films) and prevent satisfactory adhesion of the photographic emulsion to the film base.

According to the present invention these difficulties are overcome by treating the film base, before it is coated with the sensitive gelatine emulsion, for three hours or longer, with Water heated to a temperature of at least 40 C. but not exceeding 70 C. to which a small amount of ammonia has been added.- This treatment may be accomplished by submerging the film base in water (which may be renewed from time to time) at a temperature preferably between 30 and C. for 12 to 48 hours, or by drawing the film base with slow velocity throughwater which may be kept running and have the aforesaid tem perature, means being provided for removing mechanically the adherentrwater before the film is dried.

A film treated as above described will not shrink or crinkle when subjected to the usual photographic films immune from shrinkage and washing.

What I claim and desire to secure by Letters Patent is A process for rendering non-inflammable photographic films immune from shrinkage 1 or crinkling when subjected to the usual 40 C. but not exceeding 70 C. to which a small amount of ammonia has been added.

In testimony whereof, I affix my signature.

LOUIS WESTON. 

